International food and feed prices could rise by 8-20% as a result of the conflict in Ukraine, triggering a jump in the number of undernourished people around the world, the UN food agency said.

In a preliminary assessment, the Food and Agriculture Organization (FAO) said it was unclear whether Ukraine would be able to harvest during the protracted conflict, as uncertainty also ties into Russia's food exports.

The FAO said that Russia is the world's largest exporter of wheat, with Ukraine ranked fifth. Together they provide 19% of the world's supply of barley, 14% of wheat and 4% of corn, representing more than one third of world cereal exports.